HP gain with multi angle valve/seat

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Brooks James

Brooks James

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On a stock 360 magnum head
Im sure that there are many variables depending in the engine build.
Any care to offer an average amount ??
 
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Since the amount of variables are endless....... if you want to think you’re applying some logic to what is a complete guess....... you could:

Decide how much gain in flow(@28” test pressure) the new valve job will provide, in .050” lift increments, up to the lift that the valve will see.

Average those numbers, then take that result and multiply by 2 to come up with a theoretical hp gain for a v8.
 
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Average amount of what? Power added I guess? Man, that's a TOUGH one to answer since there are so many variables involved. BUT........

A lot of people don't realize that every single valve job in our older cars came right from the factory with three angles on the seat. So when a machine shop charges more for a "three angle" valve job, you're getting a stock valve job. The only thing different they do is adding a back cut to the valves.

Now, modern machines like the Serdi and Rottler like my friend Richie has that he did my slant 6 head with are a different story. They have cotters that can cut several angles at once. I think mine ended up with eight angles in the head. Crazy technology.

I think in terms of what it's "adding" would better be looked at in CFM rather than horse power. But maybe that's what you meant?
 
RustyRatRod said:
Average amount of what? Power added I guess? Man, that's a TOUGH one to answer since there are so many variables involved. BUT........

A lot of people don't realize that every single valve job in our older cars came right from the factory with three angles on the seat. So when a machine shop charges more for a "three angle" valve job, you're getting a stock valve job. The only thing different they do is adding a back cut to the valves.

Now, modern machines like the Serdi and Rottler like my friend Richie has that he did my slant 6 head with are a different story. They have cotters that can cut several angles at once. I think mine ended up with eight angles in the head. Crazy technology.

I think in terms of what it's "adding" would better be looked at in CFM rather than horse power. But maybe that's what you meant?
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I read that a multi angle added 25 hp @ 550-600 lift by adding more CFM. I having a hard time with that many cfm produced just by multi angles
 
Brooks James said:
I read that a multi angle added 25 hp by adding more CFM. I having a hard time with that many cfm produced by multi angles
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I think it's probably true with the accompanying bowl work that most "sane" people would have done at the same time, and especially with full port work. I don't think most people would do "just" a multi angle valve job and "nothing else". That doesn't sound logical, does it?
 
RustyRatRod said:
I think it's probably true with the accompanying bowl work that most "sane" people would have done at the same time, and especially with full port work. I don't think most people would do "just" a multi angle valve job and "nothing else". That doesn't sound logical, does it?
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David V says most of the flow improvement possible occurs at the seat. And the gains in flow occur by improving seat angles or installing larger valves. As you move away from the seat changes in the bowl and in the port arm can still have an impact, just not as much.
Having the right sized valves and the right seat angles are that important.
 
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my68barracuda said:
David V says most of the flow improvement possible occurs at the seat. And that is by improving seat angles or installing larger valves. As you move away from the seat changes have less of an impact.
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I would have to include the bowl in that argument. But yeah, then I'd agree.
 
It will be fun to see where this thread goes. Or doesn’t.
 
Brooks James said:
What could I expect hp wise by porting, polishing, and multi angle, 50 hp ?
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So, if you took a stock 5.2 Magnum, and did nothing but rework the heads............ with no other changes...... you’re thinking you’d see an additional 50hp out of it?
 
PRH said:
So, if you took a stock 5.2 Magnum, and did nothing but rework the heads............ with no other changes...... you’re thinking you’d see an additional 50hp out of it?
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No, full porting AND multi angle cuts. Im saying that you cant get an estra 50 hp out of a stock iron head with just porting and multi angles
 
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a stock un touch, unmolested, core shifted head, will gain a lot of CFM with a good 3 angle valve job, good intake valves and a good bowl blend. 50 HP.....could be, but, highly un likely.
 
With a custom camshaft to match the ported and modified heads an additional 50HP would not be out of the question.
 
Whats the stock lift on a stock 5.2? .430? Magnums were Hyd rollers.......it may have more them that.
 
Cudafever said:
Whats the stock lift on a stock 5.2? .430? Magnums were Hyd rollers.......it may have more them that.
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Somethin in that neighborhood. I do know all the Magnum guys "say" the 5.2 camshaft is the better of the two between the 5.2 and 5.9.
 
I guess the beer keg intake and stock exhaust manifolds are no problem then?
Redo the heads, change nothing else....... poof.... 50 more hp?

The point being........ the same level of head rework will not result in the same amount of power improvement on all combos.
 
PRH said:
I guess the beer keg intake and stock exhaust manifolds are no problem then?
Redo the heads, change nothing else....... poof.... 50 more hp?

The point being........ the same level of head rework will not result in the same amount of power improvement on all combos.
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Don't some guys mod those kegger intakes somehow and make them haul ***?
 
PRH said:
I guess the beer keg intake and stock exhaust manifolds are no problem then?
Redo the heads, change nothing else....... poof.... 50 more hp?

The point being........ the same level of head rework will not result in the same amount of power improvement on all combos.
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Redo the heads. Depends upon how far you go. 5 angle valve job with 70 degree bowl cut and bowls opened to about 88-90 percent of seat size, chambers unshrouded and last seat angle cut blended into them, and heads decked to raise compression, then 50 hp may not be out of the question.

The old mopar rags used to claim a 50hp increase just swapping a set of stock magnum heads onto an old low compression smogger LA engine.
 
RustyRatRod said:
Don't some guys mod those kegger intakes somehow and make them haul ***?
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There are some that cut the runner length shorter to raise the rpm band but I am not sure there is much to be gained there on a street engine.

Engine Masters did a dyno of the "super duper" modified kegger that UTAwesome performance works over to the tune of $700 bucks to buy one. With a small cam (218 @ .050 IIRC) it only made 10-15 more torque and hp than the stock kegger.

Probably not the best bang for the buck at least with that small cam. Maybe it is better with a longer duration cam I dunno.
 
mgoblue9798 said:
There are some that cut the runner length shorter to raise the rpm band but I am not sure there is much to be gained there on a street engine.

Engine Masters did a dyno of the "super duper" modified kegger that UTAwesome performance works over to the tune of $700 bucks to buy one. With a small cam (218 @ .050 IIRC) it only made 10-15 more torque and hp than the stock kegger.

Probably not the best bang for the buck at least with that small cam. Maybe it is better with a longer duration cam I dunno.
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Sounds like an old Street Dominator would wax its ***.
 
RustyRatRod said:
Sounds like an old Street Dominator would wax its ***.
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All depends on what you want. Torque up to 3k, beer barrel is tough to beat. Over that any good dual plane kicks its arse in all the testing and articles I have seen.
 
mgoblue9798 said:
All depends on what you want. Torque up to 3k, beer barrel is tough to beat. Over that any good dual plane kicks its arse in all the testing and articles I have seen.
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So if you have a TRUCK and use it as a TRUCK you might want the kegger. ok. ;)
 
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